1;;; rfn-eshadow.el --- Highlight `shadowed' part of read-file-name input text
2;;
3;; Copyright (C) 2000, 2001, 2002, 2003, 2004,
4;;   2005, 2006, 2007 Free Software Foundation, Inc.
5;;
6;; Author: Miles Bader <miles@gnu.org>
7;; Keywords: convenience minibuffer
8
9;; This file is part of GNU Emacs.
10
11;; GNU Emacs is free software; you can redistribute it and/or modify
12;; it under the terms of the GNU General Public License as published by
13;; the Free Software Foundation; either version 2, or (at your option)
14;; any later version.
15
16;; GNU Emacs is distributed in the hope that it will be useful,
17;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19;; GNU General Public License for more details.
20
21;; You should have received a copy of the GNU General Public License
22;; along with GNU Emacs; see the file COPYING.  If not, write to the
23;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
24;; Boston, MA 02110-1301, USA.
25
26;;; Commentary:
27;;
28;; Defines the mode `file-name-shadow-mode'.
29;;
30;; The `read-file-name' function passes its result through
31;; `substitute-in-file-name', so any part of the string preceding
32;; multiple slashes (or a drive indicator on MS-DOS/MS-Windows) is
33;; ignored.
34;;
35;; If `file-name-shadow-mode' is active, any part of the
36;; minibuffer text that would be ignored because of this is given the
37;; properties in `file-name-shadow-properties', which may
38;; be used to make the ignored text invisible, dim, etc.
39;;
40
41;;; Code:
42
43
44;;; Customization
45
46(defconst file-name-shadow-properties-custom-type
47  '(list
48    (checklist :inline t
49	       (const :tag "Invisible"
50		      :doc "Make shadowed part of filename invisible"
51		      :format "%t%n%h"
52		      :inline t
53		      (invisible t intangible t))
54	       (list :inline t
55		     :format "%v"
56		     :tag "Face"
57		     :doc "Display shadowed part of filename using a different face"
58		     (const :format "" face)
59		     (face :value file-name-shadow))
60	       (list :inline t
61		     :format "%t: %v%h"
62		     :tag "Brackets"
63		     ;; Note the 4 leading spaces in the doc string;
64		     ;; this is hack to get around the fact that the
65		     ;; newline after the second string widget comes
66		     ;; from the string widget, and doesn't indent
67		     ;; correctly.  We could use a :size attribute to
68		     ;; make the second string widget not have a
69		     ;; terminating newline, but this makes it impossible
70		     ;; to enter trailing whitespace, and it's desirable
71		     ;; that it be possible.
72		     :doc "    Surround shadowed part of filename with brackets"
73		     (const :format "" before-string)
74		     (string :format "%v" :size 4 :value "{")
75		     (const :format "" after-string)
76		     ;; see above about why the 2nd string doesn't use :size
77		     (string :format " and: %v" :value "} "))
78	       (list :inline t
79		     :format "%t: %v%n%h"
80		     :tag "String"
81		     :doc "Display a string instead of the shadowed part of filename"
82		     (const :format "" display)
83		     (string :format "%v" :size 15 :value "<...ignored...>"))
84	       (const :tag "Avoid"
85		      :doc "Try to keep cursor out of shadowed part of filename"
86		      :format "%t%n%h"
87		      :inline t
88		      (field shadow)))
89    (repeat :inline t
90	    :tag "Other Properties"
91	    (list :inline t
92		  :format "%v"
93		  (symbol :tag "Property")
94		  (sexp :tag "Value")))))
95
96(defcustom file-name-shadow-properties
97  '(face file-name-shadow field shadow)
98  "Properties given to the `shadowed' part of a filename in the minibuffer.
99Only used when `file-name-shadow-mode' is active.
100If Emacs is not running under a window system,
101`file-name-shadow-tty-properties' is used instead."
102  :type file-name-shadow-properties-custom-type
103  :group 'minibuffer
104  :version "22.1")
105
106(defcustom file-name-shadow-tty-properties
107  '(before-string "{" after-string "} " field shadow)
108  "Properties given to the `shadowed' part of a filename in the minibuffer.
109Only used when `file-name-shadow-mode' is active and Emacs
110is not running under a window-system; if Emacs is running under a window
111system, `file-name-shadow-properties' is used instead."
112  :type file-name-shadow-properties-custom-type
113  :group 'minibuffer
114  :version "22.1")
115
116(defface file-name-shadow
117  '((t :inherit shadow))
118  "Face used by `file-name-shadow-mode' for the shadow."
119  :group 'minibuffer
120  :version "22.1")
121
122
123;;; Internal variables
124
125;; A list of minibuffers to which we've added a post-command-hook.
126(defvar rfn-eshadow-frobbed-minibufs nil)
127
128;; An overlay covering the shadowed part of the filename (local to the
129;; minibuffer).
130(defvar rfn-eshadow-overlay)
131(make-variable-buffer-local 'rfn-eshadow-overlay)
132
133
134;;; Hook functions
135
136;; This function goes on minibuffer-setup-hook
137(defun rfn-eshadow-setup-minibuffer ()
138  "Set up a minibuffer for `file-name-shadow-mode'.
139The prompt and initial input should already have been inserted."
140  (when minibuffer-completing-file-name
141    (setq rfn-eshadow-overlay
142	  (make-overlay (minibuffer-prompt-end) (minibuffer-prompt-end)))
143    ;; Give rfn-eshadow-overlay the user's props.
144    (let ((props
145	   (if window-system
146	       file-name-shadow-properties
147	     file-name-shadow-tty-properties)))
148      (while props
149	(overlay-put rfn-eshadow-overlay (pop props) (pop props))))
150    ;; Turn on overlay evaporation so that we don't have to worry about
151    ;; odd effects when the overlay sits empty at the beginning of the
152    ;; minibuffer.
153    (overlay-put rfn-eshadow-overlay 'evaporate t)
154    ;; Add our post-command hook, and make sure can remove it later.
155    (add-to-list 'rfn-eshadow-frobbed-minibufs (current-buffer))
156    (add-hook 'post-command-hook #'rfn-eshadow-update-overlay nil t)))
157
158(defsubst rfn-eshadow-sifn-equal (goal pos)
159  (equal goal (condition-case nil
160		  (substitute-in-file-name
161		   (buffer-substring-no-properties pos (point-max)))
162		;; `substitute-in-file-name' can fail on partial input.
163		(error nil))))
164
165;; post-command-hook to update overlay
166(defun rfn-eshadow-update-overlay ()
167  "Update `rfn-eshadow-overlay' to cover shadowed part of minibuffer input.
168This is intended to be used as a minibuffer `post-command-hook' for
169`file-name-shadow-mode'; the minibuffer should have already
170been set up by `rfn-eshadow-setup-minibuffer'."
171  (condition-case nil
172      (let ((goal (substitute-in-file-name (minibuffer-contents)))
173            (mid (overlay-end rfn-eshadow-overlay))
174            (start (minibuffer-prompt-end))
175            (end (point-max)))
176        (unless
177            ;; Catch the common case where the shadow does not need to move.
178            (and mid
179                 (or (eq mid end)
180                     (not (rfn-eshadow-sifn-equal goal (1+ mid))))
181                 (or (eq mid start)
182                     (rfn-eshadow-sifn-equal goal mid)))
183          ;; Binary search for the greatest position still equivalent to
184          ;; the whole.
185          (while (or (< (1+ start) end)
186                     (if (and (< (1+ end) (point-max))
187                              (rfn-eshadow-sifn-equal goal (1+ end)))
188                         ;; (SIFN end) != goal, but (SIFN (1+end)) == goal,
189                         ;; We've reached a discontinuity: this can happen
190                         ;; e.g. if `end' point to "/:...".
191                         (setq start (1+ end) end (point-max))))
192            (setq mid (/ (+ start end) 2))
193            (if (rfn-eshadow-sifn-equal goal mid)
194                (setq start mid)
195              (setq end mid)))
196          (move-overlay rfn-eshadow-overlay (minibuffer-prompt-end) start)))
197    ;; `substitute-in-file-name' can fail on partial input.
198    (error nil)))
199
200(define-minor-mode file-name-shadow-mode
201  "Toggle File-Name Shadow mode.
202When active, any part of a filename being read in the minibuffer
203that would be ignored (because the result is passed through
204`substitute-in-file-name') is given the properties in
205`file-name-shadow-properties', which can be used to make
206that portion dim, invisible, or otherwise less visually noticeable.
207
208With prefix argument ARG, turn on if positive, otherwise off.
209Returns non-nil if the new state is enabled."
210  :global t
211  :init-value t
212  :group 'minibuffer
213  :version "22.1"
214  (if file-name-shadow-mode
215      ;; Enable the mode
216      (add-hook 'minibuffer-setup-hook 'rfn-eshadow-setup-minibuffer)
217    ;; Disable the mode
218    (remove-hook 'minibuffer-setup-hook 'rfn-eshadow-setup-minibuffer)
219    ;; Remove our entry from any post-command-hook variable's it's still in
220    (dolist (minibuf rfn-eshadow-frobbed-minibufs)
221      (with-current-buffer minibuf
222	(remove-hook 'post-command-hook #'rfn-eshadow-update-overlay t)))
223    (setq rfn-eshadow-frobbed-minibufs nil)))
224
225
226(provide 'rfn-eshadow)
227
228;; arch-tag: dcf70a52-0115-4ec2-b1e3-4f8d3541a888
229;;; rfn-eshadow.el ends here
230